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Introduction to Particle Detectors

Introduction to Particle Detectors. Robert W. Lambert, NIKHEF, FOM, VU Amsterdam, NL. cern.ch/ rlambert /lectures. rob.lambert@cern.ch. Outline. Outline. … so, usually this is a 28-hour lecture series … We have time for: A historical overview … how did we get here?

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Introduction to Particle Detectors

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  1. Introduction to Particle Detectors Robert W. Lambert, NIKHEF, FOM, VU Amsterdam, NL cern.ch/rlambert/lectures rob.lambert@cern.ch Nikhef, 1st March 2013

  2. Nikhef, 1st March 2013

  3. Outline Nikhef, 1st March 2013

  4. Outline • … so, usually this is a 28-hour lecture series … • We have time for: • A historical overview … how did we get here? • Particle physics … what are we trying to do now? • Particle interactions with matter … how do we detect anything? • General overview of a huge “detector” • We don’t have time for: • Specific technology discussions • An example of the many hundreds of detectors/technologies • Discussions of limitations and design constraints Nikhef, 1st March 2013

  5. Part 1 A historical overview. Nikhef, 1st March 2013

  6. The first detector? • Take a guess? Nikhef, 1st March 2013

  7. The first detector Nikhef, 1st March 2013

  8. The first DAQ? • Take a guess? Nikhef, 1st March 2013

  9. The first DAQ Nikhef, 1st March 2013

  10. Delving into Matter 450 BCE: Empedocles: 4 elements Nikhef, 1st March 2013

  11. Delving into Matter 450 BCE: Empedocles: 4 elements 440 BCE: Atomists (Leucippus and Democritus) 360 BCE: Elementists (Plato) Nikhef, 1st March 2013

  12. Delving into Matter 1310: Pseudo-Geber: Metals Sulphur Nikhef, 1st March 2013

  13. Delving into Matter Titration, distillation, glassware … Discovery of many other “elements” 1310: Pseudo-Geber: Metals Proust: Law ofDefinite Proportions Mass Conservation Boyle’s Law Alchemy 1794 1310 Definition of “the scientific method” A theory of chemical reactions 1310: Pseudo-Geber: Metals Nikhef, 1st March 2013

  14. Birth of Particle Physics • 1815: Prout, a practising physician and amateur chemist: • The atomic mass of all elements are an integer multiple of the mass of hydrodgen • Atoms primarily consist of an integer number of “protyle”s • 1897: Thomson (primarily a mathematician) • Discovers the electron -> Plum-pudding Model • Sea of positive charge with embedded electrons, overall neutral 1896:Bequerel: Radioactivity 1794: Proust: Elements 1869:Lenard:Cathode Rays 1895:Roentgen: X-rays 1911: Rutherford et al The Nucleus 1911 ~1896 1869 1794 1815 Nikhef, 1st March 2013

  15. Birth of Particle Physics • 1815: Prout, a practising physician and amateur chemist: • The atomic mass of all elements are an integer multiple of the mass of hydrodgen • Atoms primarily consist of an integer number of “protyle”s • 1897: Thomson (primarily a mathematician) • Discovers the electron -> Plum-pudding Model • Sea of positive charge with embedded electrons, overall neutral 1896:Bequerel: Radioactivity 1794: Proust: Elements 1869:Lenard:Cathode Rays What Happened Here?? 1895:Roentgen: X-rays 1911: Rutherford et al The Nucleus 1911 ~1896 1869 1794 1815 Nikhef, 1st March 2013

  16. 1866 • In 1866, Zinc Sulphide (doped with impurities like copper) was discovered to glow through phosphorescence • 1866: ZnS … 1869: Cathode rays • 1880: Becquerel studying all forms of luminescence 1869, discovery of “cathode rays”Nobel Prize for Physics in 1905 for Phillipe Lenard (unfortunately a nazi :S ) Just the first example of how a new detector drovenew discoveries … we’ll see many more over the next few lectures! Nikhef, 1st March 2013

  17. Discovering X-rays • X-rays could not be discovered before photographic plates and scintillators • Roentgen, x-rayed his wife’s hand … won a nobel prize Nikhef, 1st March 2013

  18. Thomson • Mathematician who did physics as a hobby • Nobel Prize in 1906, "in recognition of the great merits of his theoretical and experimental investigations on the conduction of electricity by gases." “He estimated the mass of cathode rays by measuring the heat generated when the rays hit a thermal junction and comparing this with the magnetic deflection of the rays.” .. First particle physics calorimeter??... A new detector! Nikhef, 1st March 2013

  19. Thomson • Mathematician who did physics as a hobby • Nobel Prize in 1906, "in recognition of the great merits of his theoretical and experimental investigations on the conduction of electricity by gases." Mass to charge ratio with a modified Crookes tube Nikhef, 1st March 2013

  20. Geiger-Marsden • Two of Rutherford’s students… • Spent weeks counting thousands of particles … Nikhef, 1st March 2013

  21. Rutherford “It was quite the most incredible event that has ever happened to me in my life. It was almost as incredible as if you fired a 15-inch shell at a piece of tissue paper and it came back and hit you. On consideration, I realized that this scattering backward must be the result of a single collision, and when I made calculations I saw that it was impossible to get anything of that order of magnitude unless you took a system in which the greater part of the mass of the atom was concentrated in a minute nucleus. It was then that I had the idea of an atom with a minute massive center, carrying a charge” • Ernest Rutherford (nobel prize in 1908) Nikhef, 1st March 2013

  22. Masses made no sense Nikhef, 1st March 2013

  23. Neutron Nikhef, 1st March 2013

  24. Neutron • How do you detect a heavy, neutral (invisible) particle? • Watch what happens when it hits stuff • 1930: Bothe and Becker: • bombardment of beryllium with alpha particles produces neutral radiation which is penetrating but non-ionizing • Curie and Joliot showed that when you bombarded a paraffin target with this radiation, it ejected protons with energy about 5.3 MeV • 1930-4: Chadwick and Rutherford got together … Nikhef, 1st March 2013

  25. Chadwick • (Nobel prize, 1935) • Chadwick used many materials, and … oh, what’s that? Nikhef, 1st March 2013

  26. Chadwick • (Nobel prize, 1935) • Chadwick used many materials, and … oh, what’s that? • A new type of detector, the Geiger Muller tube. • Invented in 1928, Neutron experiments start in 1930 Nikhef, 1st March 2013

  27. Birth of Particle Physics 1932: Chadwick: Neutron 1932 Nikhef, 1st March 2013

  28. Birth of Particle Physics Prout started this all off …. But …. 1932: Chadwick: Neutron 1932 Nikhef, 1st March 2013

  29. Prout was wrong! Nikhef, 1st March 2013

  30. Since then … • It took 2000 years to go from 4->7 elements • It took 500 years to go from 7 -> 100 elements • It took 100 years to discover the modern atom • That was only 100 years ago … • … surely not much can be different now… right? New Accelerators New Questions New Discoveries New Predictions New Detectors Nikhef, 1st March 2013

  31. Compare a century 1909 Geiger Marsden. 1 channel. 1 event/second 2009 Atlas. 108 channels. 106 events/second ~ 50 m ~ 3000 physicists ~ 20 cm~ 3 physicists Nikhef, 1st March 2013

  32. Part 2 Properties of Matter and Particles useful for detection Nikhef, 1st March 2013

  33. Part 2 • Particles can only be detected if they leave some sort of record behind • Ideally this should be something we also can detect… • Now we will discuss all those things that can happen, and why they are interesting to us Nikhef, 1st March 2013

  34. Hitting things Nikhef, 1st March 2013

  35. Detector types? Charged Particles All Particles TRACKING Transition Radiation TRD DIRC Bubble chamber Cherenkov Time of flight(TOF) Particle ID (PID) Muon System Spectrometry Calorimetry: HCAL / ECAL Cloud Chamber dE/dX Pixels Particle Flow Scintilators Strips Material Damage Chemical Change Wire Chambers Straw Tubes Thermal effects Time Projection Chamber Knock-on effects Absorption/Destruction Nikhef, 1st March 2013

  36. What to detect? • The Standard Model comprises a “particle zoo” • How can we tell what is what? ~50 types of observable baryons ~50 types observable anti-baryons 25 types ofobservableMesons Nikhef, 1st March 2013

  37. What to detect? • The Standard Model comprises a “particle zoo” • How can we tell what is what? ~50 types of observable baryons ~50 types observable anti-baryons 25 types ofobservableMesons Nikhef, 1st March 2013

  38. Final State Particles Nikhef, 1st March 2013

  39. Everything Else? • Particles with insufficient lifetime to enter the detector f = final state, m particles 4-vectors Charges Spins i = initial state, 1 particles lif is a lifetime, which can be accessedby the decay length in the detector Nikhef, April/May 2012

  40. “General Purpose” • To get to the QM “observables” we need to translate • Energy deposits (hits) => Matrix elements • Identify each final-state particle uniquely • Identifies every Q • Identifies sets of possible spin states • Determine the particle’s momentum vector • Integrated over spins (if the observable is accessible like that) • Analyse with respect to angles if spins are required • Determine decay lengths Nikhef, April/May 2012

  41. Part 3 Building the right detector Nikhef, 1st March 2013

  42. An LHC-like “Detector” Normally arranged in concentric cylinders around the vertex position TRACKING Particle ID (PID) Spectrometer(detector planes) Straws?Wires? TPC? Calorimeter Sampling? Particle Flow? Compen-sating? Muons Straw tubes (usually) Charged TOF? Cherenkov? TRD? dE/dX ? Magnet ~ T Vertexing Silicon Strips? Silicon Pixels? Nikhef, 1st March 2013

  43. Separating Out Nikhef, 1st March 2013

  44. Separating Out Tracking, Separate Charged and Neutral Nikhef, 1st March 2013

  45. Separating Out Calorimetry, Separate Hadrons from EM Nikhef, 1st March 2013

  46. Separating Out Charged PID, TRD, Cherenkov, TOFSeparate charged hadrons Kinematic constraints 0.494 GeVc-2 0.140 GeVc-2 0.938 GeVc-2 Nikhef, 1st March 2013

  47. Kinematic Constraints • Masses of p/K/p, n/KL are different • Determine which is the “correct” hypothesis from kinematics • Apart from the complication of … Correct Mass Hypothesis too low Mass Hypothesis too high Reconstructed Mother Mass A.U. Nikhef, April/May 2012

  48. Backgrounds • Knowing the ID of the signal you’re looking for is easy • Separating it from the continuum background is not easy! • The main challenge at a hadron machine • Find as many separating variables as possible … need PID Nikhef, April/May 2012

  49. Part 4 LHCb : A precision experiment Nikhef, 1st March 2013

  50. Top-down Nikhef, April/May 2012

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